Preparation of low temperature poly-silicon (LTPS) thin films is usually conducted in a laser crystallization manner, and an excimer laser is used as a heat source. A laser beam with evenly distributed energy may be obtained from laser light having passed through a projection system, and is projected on a glass substrate having an amorphous silicon structure formed thereon; after the amorphous silicon structure on the glass substrate absorbs the energy of the excimer laser, it can be converted into a polysilicon structure. As the whole treating process is accomplished below 600° C., common glass substrates are all suitable for the above method. FIG. 1 is a structurally schematic view illustrating a TFT (thin film transistor) array substrate having an LTPS film, and as for manufacturing of the array substrate, it is necessary that an amorphous silicon (a-si) thin film layer 3 be deposited on a SiOx/SiNx buffer layer 2 of a glass substrate 1, as shown in FIG. 2; and a laser crystallizing treatment is carried out on the amorphous silicon thin film layer 3, so that a polysilicon (P—Si) thin film layer 6 is obtained from it, as shown in FIG. 3; after that, a patterning process is performed, so as to form an active layer 4 of a TFT switch 5.
In the course of solidifying the low-temperature polysilicon, the amorphous silicon thin film layer 3 is firstly deposited on the buffer layer 2 of the glass substrate 1 in FIG. 2, and then is subjected to a laser annealing crystallization treatment so as to form the polysilicon thin film layer 6, as shown in FIG. 3.